Device for receiving high frequency currents superimposed on electrical power supply lines



April 2, 1935. M CHIRQL 1,996,145 DEVICE FOR RECEIVING HIGH FREQUENCYCURRENTS SUPERIMPOSED on ELECTRICAL POWER SUPPLY LINES Filed Jan. 19,1933 trical power supply systems, for actuating certain Patented Apr. 2,1935 UNITED STATES PATENT OFFICE DEVICE FOR RECEIVING HIGH FREQUENCYCURBENTS SUPERIMPOSED ON TRICAL-POWER SUPPLY LINES ELEC- ApplicationJanuary 19, 1933, Serial No. 652,559 In France August ,24, 1932 5 Claim.

it has already been proposed to superimpose high frequency currents,particularly currents the frequency of which corresponds to that of amusical note, on normal supply currents in elecmembers or certainapparatus, usually relays, responsive to high frequencies and adapted toperform definite duties under the influence of such currents, forexample the change of tarifi in multiple tariff meters.

Such receiving members or apparatus which are usually located in the lowtension portion of the system, (whereas the superimposed currents may befed into the high tension portion thereof) are, in general, adapted tooperate normally when the voltage of the superimposed currents varieswithin certain limits; so as to provide for the possible increases ordrops in the voltage thereof but such limits are necessarily narrow.

The object oi this invention is to make said apparatus operate normallywithin considerably wider limits. t

In the systems proposed hitherto, the superimposed currents act directlyon the receiving member. which is usually a resonance relay connectedacross the supply circuit.

According to the invention, the addition of an auxiliary circuit enablesany receiver of superimposed currents to respond to two influencessimultaneously.

(a) To an influence dependent upon the voltage of such currentsavailable at the input, as is normally the case;

(b) To an influence dependent upon the amperage of such currents in thelow tension leads of the system, and due to the currents induced in theaforesaid auxiliary circuit.

As will be hereinafter explained, the action according to (b) increasesas the terminal impedance of the low tension system decreases for thesuperimposed currents; it will also be seen that this is equivalent tosaying: The action according to (b) increases as the action according to(a) decreases."

Consequently, the auxiliary circuit according to the invention acts asan auto-compounding circuit" for supplying the superimposed currentreceivers, and enables the total action of such currents to bemaintained substantially constant, (1'. e. substantially independent ofthe local conditions of the receiver) A further object of the presentinvention is to prevent fraudulent tampering with a remotely controlleddevice for changing the tariff of a multiple tarifi meter.

example, currents of the frequency of a musical note) placed in serieswith the line as at 3, or in parallel as at 3', according to the methodused for superimposing; 4 is a step down transformer by means of whichthe terminal impedance 6, which maybe of any kind, can be supplied withcurrent by the source 2 through the low tension line 5 and 5'. l and 8are respectively the condenser and the winding of a receiving relay, e.g. of the resonance type. I

According to the present invention and as illustrated in Figure 2, thereare added to the elements illustrated in Figure 1, an auxiliary circuitcomprising a transformer, the primary winding Hi of which is in serieswith the low tension leads and the secondary winding of which suppliesthe supplementary winding 9 located on the receiving relay. The windings8 and 9 of said relay have entirely separate magnetic circuits which donot react on each other and the currents passing through them act in thesame direction, and are consequently additive in their action on themoving members of the relay.

In Figure 3, the auto compounding auxiliary circuit still comprises thetransformer l0-l l,

but its secondary winding ll supplies the coil 8 of the receiving relaydirectly, the additional coil 9 of Figure 2 being eliminated. Acondenser I4 is inserted in this circuit, either to prevent the currentfrom the mains from entering the receiver, or to tune the auxiliarycircuit, or to bring into phase the superimposed current directlyentering the coil 8, and the current supplied thereto by the transformerIll-ll, or to carry out simultaneously all of the above enumeratedduties, or finally for any other purpose which may be considerednecessary. 7

According to Figure 4, the transformer l0-ll of the auxiliary autocompounding circuit is replaced by an auto-transformer l2l3, a portionof the winding of which aids in supplying the coil 8 of the receivingrelay, the condenser it being retained or not.

Finally, inFigure 5the transformer lil-ii is again replaced by anauto-transformer i2i3, the whole winding of which is, in this case, usedto aid in supplying the coil 8 of the receiving relay, the condenser Mbeing again retained or not, and a condenser i5 being added, ifnecessary, across the coil 8 in order to increase the voltage across thelatter.

If the voltage of the superimposed currents across the coil 8 remainsstationary or retains a mean value during a fairly restricted period ofvariations, the ordinary known device of Figure 1 is suflicient toensure the correct operation of the receiving relay. But for atransformer d of given characteristics, account must be taken of thefact that the limits of the period of variations of the voltage of thesuperimposed currents are essentially dependent on the value and thenature of the terminal impedance 6 fed by said transformer. Inparticular, such impedance may retain a normal value for the supplycurrents which is in keeping with the power of the transformer d, but atthe same time if a disturbing circuit, illustrated in the drawing by thecapacity ll and inductance i8, is connected to the system accidentallyor intentionally by the subscriber with fraudulent intent, i. e. toprevent the change tariff device associated with the meter fromfunctioning, the said impedance may fall to a value far below that whichis normally provided for the superimposed currents; in the latter case aconsiderable increase of such currents supplied by the transformerloccurs and, asa result thereof, a greater voltage drop across thereactance of said transformer and the impedance of the lines 5 and 5';this finally causes a decrease in the voltage of the superimposedcurrents available across the coil 8 of the receiving relay. While thedisturbing circuit i7i8 must have a very low impedance; for the highfrequency currents,

- it is evident t it must have a high impedance vice of Figure l, thesuperimposed currents which pass through either the primary winding iiiof the transformer ld-i i, or the portion ii of the winding of the autotransformer i2 l3, induce, in said auxiliary circuit, currents, thevalue of which, for aiding in supplying the receiver, increases with theactual value of said currents, i. e., as the terminal impedance 6.decreases.

, continuous or damped, or are modulated or not at the transmitting end,or detected or not at the receiving end, etc.

In general, any addition to an auxiliary circuit, whatever may be itsform or its structure,

placed either in the receiver or in thevicinity thereof, and the eflectof which is to produce on the moving members of the latter, an action ofsuperimposed currents which increases as the terminal impedance of thesupply mains decreases for their frequency, will be considered to fallwithin the scope of the invention.

Furthermore, such an auxiliary or auto com pounding circuit with respectto the receiver which is the object of the invention, will have noappreciable action on the normal supply currents.

I claim:

1. In a low frequency electric supply network comprising a high tensionside on which currents of higher frequency are superimposed, a lowtension side and a step-down transformer connecting said high to saidlow tension side, the combination with a relay including a windingshunted across said low tension side and responsive to said superimposedcurrents, of a second transformer having a primary winding mounted inseries in the low tension side of said network and the secondary ofwhich cooperates with the winding of said relay, said second transformerbeing adapted to induce in its secondary a current which increasesproportionately to any decreases of the current flowing through saidrelay winding.

2. System according to claim 1 in combination with a winding connectedto mid second transformer secondary and cooperating with said relaywinding to compensate the decrease of current 4i;

